我已经开发了一个随机字符串生成器，但它的行为并不像我所希望的那样。我的目标是能够运行两次，并生成两个不同的四字符随机字符串。但是，它只生成一个四个字符的随机字符串两次。
下面是代码和输出示例:
private string RandomString(int size)
{
StringBuilder builder = new StringBuilder();
Random random = new Random();
char ch;
for (int i = 0; i < size; i++)
{
ch = Convert.ToChar(Convert.ToInt32(Math.Floor(26 * random.NextDouble() + 65)));
builder.Append(ch);
}
return builder.ToString();
}
// get 1st random string
string Rand1 = RandomString(4);
// get 2nd random string
string Rand2 = RandomString(4);
// create full rand string
string docNum = Rand1 + "-" + Rand2;
.．.输出如下:UNTE-UNTE
.．.但它应该看起来像这个UNTE-FWNU
如何确保两个明显随机的字符串?
public static class StringHelpers
{
public static readonly Random rnd = new Random();
public static readonly string EnglishAlphabet = "abcdefghijklmnopqrstuvwxyz";
public static readonly string RussianAlphabet = "абвгдеёжзийклмнопрстуфхцчшщъыьэюя";
public static unsafe string GenerateRandomUTF8String(int length, string alphabet)
{
if (length <= 0)
return String.Empty;
if (string.IsNullOrWhiteSpace(alphabet))
throw new ArgumentNullException("alphabet");
byte[] randomBytes = rnd.NextBytes(length);
string s = new string(alphabet[0], length);
fixed (char* p = s)
{
for (int i = 0; i < s.Length; i++)
{
*(p + i) = alphabet[randomBytes[i] % alphabet.Length];
}
}
return s;
}
public static unsafe string GenerateRandomUTF8String(int length, params UnicodeCategory[] unicodeCategories)
{
if (length <= 0)
return String.Empty;
if (unicodeCategories == null)
throw new ArgumentNullException("unicodeCategories");
if (unicodeCategories.Length == 0)
return rnd.NextString(length);
byte[] randomBytes = rnd.NextBytes(length);
string s = randomBytes.ConvertToString();
fixed (char* p = s)
{
for (int i = 0; i < s.Length; i++)
{
while (!unicodeCategories.Contains(char.GetUnicodeCategory(*(p + i))))
*(p + i) += (char)*(p + i);
}
}
return s;
}
}
你还需要这个:
public static class RandomExtensions
{
public static string NextString(this Random rnd, int length)
{
if (length <= 0)
return String.Empty;
return rnd.NextBytes(length).ConvertToString();
}
public static byte[] NextBytes(this Random rnd, int length)
{
if (length <= 0)
return new byte[0];
byte[] randomBytes = new byte[length];
rnd.NextBytes(randomBytes);
return randomBytes;
}
}
这:
public static class ByteArrayExtensions
{
public static string ConvertToString(this byte[] bytes)
{
if (bytes.Length <= 0)
return string.Empty;
char[] chars = new char[bytes.Length / sizeof(char)];
Buffer.BlockCopy(bytes, 0, chars, 0, bytes.Length);
return new string(chars);
}
}
我创建了这个方法。
效果很好。
public static string GeneratePassword(int Lenght, int NonAlphaNumericChars)
{
string allowedChars = "abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNOPQRSTUVWXYZ0123456789";
string allowedNonAlphaNum = "!@#$%^&*()_-+=[{]};:<>|./?";
Random rd = new Random();
if (NonAlphaNumericChars > Lenght || Lenght <= 0 || NonAlphaNumericChars < 0)
throw new ArgumentOutOfRangeException();
char[] pass = new char[Lenght];
int[] pos = new int[Lenght];
int i = 0, j = 0, temp = 0;
bool flag = false;
//Random the position values of the pos array for the string Pass
while (i < Lenght - 1)
{
j = 0;
flag = false;
temp = rd.Next(0, Lenght);
for (j = 0; j < Lenght; j++)
if (temp == pos[j])
{
flag = true;
j = Lenght;
}
if (!flag)
{
pos[i] = temp;
i++;
}
}
//Random the AlphaNumericChars
for (i = 0; i < Lenght - NonAlphaNumericChars; i++)
pass[i] = allowedChars[rd.Next(0, allowedChars.Length)];
//Random the NonAlphaNumericChars
for (i = Lenght - NonAlphaNumericChars; i < Lenght; i++)
pass[i] = allowedNonAlphaNum[rd.Next(0, allowedNonAlphaNum.Length)];
//Set the sorted array values by the pos array for the rigth posistion
char[] sorted = new char[Lenght];
for (i = 0; i < Lenght; i++)
sorted[i] = pass[pos[i]];
string Pass = new String(sorted);
return Pass;
}
实际上，一个好的解决方案是为随机数生成器提供一个线程安全且不使用锁的静态方法。
这样，同时访问web应用程序的多个用户就不会得到相同的随机字符串。
这里有3个例子:
http://blogs.msdn.com/b/pfxteam/archive/2009/02/19/9434171.aspx
我会用最后一个:
public static class RandomGen3
{
private static RNGCryptoServiceProvider _global =
new RNGCryptoServiceProvider();
[ThreadStatic]
private static Random _local;
public static int Next()
{
Random inst = _local;
if (inst == null)
{
byte[] buffer = new byte[4];
_global.GetBytes(buffer);
_local = inst = new Random(
BitConverter.ToInt32(buffer, 0));
}
return inst.Next();
}
}
然后就可以适当消去了
Random random = new Random();
只需调用RandomGen3.Next()，而您的方法可以保持静态。
